The U.S. government on Friday voiced deep concern over Zhu Yufu’s reported sentencing and the recent convictions of three other dissidents who have received nine- and 10-year prison terms for subversion or inciting subversion over the last few months.

A court in Hangzhou city sentenced dissident Zhu on Friday in a hearing attended by his ex-wife and son, said the Chinese Human Rights Defenders. Zhu’s ex-wife and lawyers could not immediately be reached.

Zhu is among a group of writers and intellectuals targeted by Chinese authorities in a crackdown aimed at preventing Arab Spring-style popular uprisings.

Human rights activists have criticized the ruling party’s use of vague subversion laws to jail its critics. Authorities began using the subversion law against activists after repealing a widely criticized law on counterrevolutionary activities.

Zhu’s lawyer Li Dunyong said previously that during the trial, prosecutors cited as evidence a poem Zhu wrote titled “It’s Time.” Sections of the poem have since been widely shared on the Internet. Part of it reads: “It’s time, Chinese people! The square belongs to every one. Your feet are your own. It’s time to use your feet to go to the square and make a choice.”

Zhu sent the poem to friends via the Internet early last year as anonymous calls circulated online urging Chinese to imitate protests that toppled governments in North Africa and the Middle East.

Prosecutors said “It’s Time” was meant to encourage Chinese to stage their own anti-government protests, Li said. He said that Zhu denied the charges and denied posting the poem to any public online forum. He said he shared it only with friends.

In Washington, State Department spokeswoman Victoria Nuland called for the release of Zhu and all others “detained for exercising their rights.” She said she expected human rights to be raised during vice president Xi’s visit to the U.S. next week.

“We remain more broadly deeply concerned about the worsening human rights situation in China, including the Chinese government’s harsh sentences of human rights activists and recent violence in Tibetan areas,” she told a news briefing.